I suggest going to that site and replace their canned letter with this one:
Dear Caterpillar Corporation:
Various leftist anarchist, self-styled "peace" groups, known variously as International Solidarity Movement, Act Now to Stop War and End Racism, Jewish Voice for Peace [sic!], ProgressivePortal.org, have trespassed on your corporate field offices, threatened your employees, and have made videos of themselves in which they promise to return and continue their harrassment until you submit to their demands.
This is more than enough evidence for you to file legal action against them for harrassment and intimidation according to federal RICO statutes.
I hope you will pursue legal action against this unlawful trespass against your rights as a corporation to conduct business.
Sincerely,
A supporter of Caterpillar Corporation!